This application for a Mentored Research Scientist Development Award (K01) is a re-submission by a new investigator. The goal of the award is to provide the investigator further training in the fields of obesity and community health nursing. As part of this training, the investigator will receive mentoring and pursue academic study in the following areas: 1) etiology and complications of obesity; 2) behavioral treatment of obesity; 3) community health nursing; 4) conduct of clinical trials; 5) exercise physiology; 6) biostatistics; and 7) nutrition. The proposal builds on a background in cardiovascular research, clinical study of weight loss maintenance, and community-based activities. Recent data show that 61% of US adults are overweight or obese. As a result, there is an epidemic of obesity-related health problems such as diabetes, coronary artery disease, and high blood pressure. Losses of only 5% to 10% of body weight significantly improve health, and individuals in programs that modify diet and lifestyle typically achieve weight losses of this magnitude. Unfortunately, the great majority of people cannot maintain the loss. Regular exercise is crucial to the maintenance of weight loss, but most individuals have problems with adherence due to a variety of barriers to exercise. Typical barriers are lack of time, lack of childcare, and lack of access to facilities. The goal of the proposed research is to improve the maintenance of weight loss by increasing physical activity in a low-income, primarily African American population that participates in a community-based behavioral weight loss program. All participants (n=152) will be treated with a 20-week weight reduction program followed by 52 weeks of maintenance. At the outset of the study, subjects will be randomized to one of two physical activity conditions. The research has two specific aims: The first is to compare at week 72 the maintenance of weight loss and physical activity adherence in individuals who are prescribed a standard structured exercise program of walking (Condition 1) versus a lifestyle activity intervention self-monitored via pedometer (Condition 2). Adherence will be determined by obtaining a common measure of physical activity across both conditions using accelerometers. The second aim is to compare short- (week 20) and long-term (week 72) differences between the two conditions in measures of physical (serum lipids, glucose/insulin ratio, interleukin-6, C-reactive protein, resting blood pressure, cardiorespiratory fitness) and psychosocial health (mood, quality of life). This study has been selected to further develop the investigator's knowledge of the treatment of obesity using principles of community health nursing, and the training has been designed to facilitate the investigator's development as an independent clinical scientist studying innovative ways of reducing cardiovascular risks within urban communities.